Yeah i managed to make a fully functional fight using sephiroth.
Dude! I can see it now... an epic battle with shadow-cloud! Perhaps as a final fight?
FINAL BATTLE LOCATION: 3 enemies...
1:Shadow Aerith: Sephiroth messing with Cloud's mind, making him think that Aerith blamed him for her death.
2:Shadow Cloud: Cloud confronting his inner darkness/inner Jenova to be at peace with himself(temporarily) so he could face Sephiroth.
3:Sephiroth: Final fight to "Banish" Sephiroth and save the planet!!!